DNA microarrays have been used to measure gene expression in tumor samples from patients and to facilitate diagnosis. Gene expression can reveal the presence of cancer in a patient, its type, stage, and origin, and whether genetic mutations are involved. Gene expression may even have a role in predicting the efficacy of chemotherapy. Over recent decades, the National Cancer Institute (NCI) has tested compounds, including chemotherapy agents, for their effect in limiting the growth of 60 human cancer cell lines. The NCI has also measured gene expression in those 60 cancer cell lines using DNA microarrays. Various studies have explored the relationship between gene expression and compound effect using the NCI datasets. During chemotherapy for cancers critical time is often lost due to a trial and error approach to finding an effective therapy. In addition, cancer cells often develop resistance to a previously effective therapy. In such situations, patient outcome would be greatly improved by early detection of such resistance.
There remains a need for proven methods and devices that predict the sensitivity or resistance of cancer patients to a medical treatment.